<!--星空背景-->
<div class="star-bg">
    <canvas id="starts"></canvas>
</div>
<script>
    var star_num = Math.sqrt(Math.pow(window.outerHeight,2)+Math.pow(window.outerWidth,2))/10;
    canvas("starts",255,star_num,100,2,500000,0.4);
</script>
<!--星空背景-->